(1) Field of the Invention
This invention relates to a novel benzothiazine derivative, a process for the preparation of same, and a pharmaceutical composition (in particular, an anti-inflammatory composition) containing same.
(2) Description of the Prior Art
In the past, aspirin, fenoprofen and the like were used as anti-inflammatory, analgesic and antipyretic agents. More recently, indomethacin, diclofenac and the like came into common use because of their high anti-inflammatory activity. However, these compounds have such disadvantages as a high degree of toxicity, a high incidence of gastric disorders, a short duration of action, and the like.
Accordingly, Piroxicam [3,4-dihydro-2-methyl-4-oxo-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxami de 1,1-dioxide] and Sudoxicam [3,4-dihydro-2-methyl-4-oxo-N-(2-thiazolyl)-2H-1,2-benzothiazine-3-carboxa mide 1,1-dioxide] have been developed as long-acting anti-inflammatory agents of the benzothiazine series (U.S. Pat. No. 3,591,584). Although these compounds have a potent and long-lasting anti-inflammatory activity, their high degree of toxicity and high incidence of gastric disorders are not appreciably different from those of indomethacin and diclofenac.
Meanwhile, Isoxicam [3,4-dihydro-2-methyl-N-(5-methyl-3-isoxazolyl)-4-oxo-2H-1,2-benzothiazine -3-carboxamide 1,1-dioxide] has also been developed as an anti-inflammatory agent (Japanese Patent Laid-Open No. 29373/'72). This compound has an isoxazole structure, so that its degree of toxicity and incidence of gastric disorders are relatively low. However, its anti-inflammatory activity is lower than that of Piroxicam and Sudoxicam.